I am having problems making my engine play a decent game on 19x19 board. Some KGS games exposed the following problems.
1) Ladder problem. It often mis-evaluates ladders despite my best efforts to detect them in the playouts. So I resorted to doing qsearch at the root to weed out moves which loose tactically, and make winning moves immediately. That helped but sometimes the qsearch explodes and engine looses on time. I tried putting a limit to the depth of qsearch but it still runs into problems. Using a small depth limit may help in 9x9 but on 19x19, atleast 40 plies is required to detect one ladder along the diagonal... so what to do ? 2) My second problem concerns use of progressive widening/unpruning which looks like a must to have on 19x19. The problem I have is with the move ordering... If I tell it to moves on the 3rd line from the edge are good ones, it continually puts its stones on that line (hence forming a square), while the opponent controls the centre and also cuts some parts of the 3rd line. Then I used fillboard to try and fix this issue, but the engine once again tends to prefer these moves and put stones all over the board. Which is when I realized it is impossible to fix it with static move ordering. Should I use something dynamic like RAVE to order the moves? That will be inconvinient because I order the nodes only during first allocation. Also the default progressive unpruning formula seems to select too few moves for consideration, so I had to add 20 additional moves to make it work for my engine.
_______________________________________________ Computer-go mailing list [email protected] http://dvandva.org/cgi-bin/mailman/listinfo/computer-go
